Alans evil riddle #24 was published on Friday post.
If I am πrl then my cousins are +/- me!
What am I?
What do we look like?
What is our origin?
Answers: Kelda : Cone-in-cone structures in limestone.
Cone-in-cone structures are secondary sedimentary structures that form in association with deeper burial and diagenesis. They consist of concentric inter-bedded cones of calcite or more rarely gypsum, siderite or pyrite. Although several mechanisms may be responsible for the formation of cone-in-cone structures, displacive crystal mechanism is preferred. It accounts for the most uniform and consistent explanation of growth and why cone-in-cone can occur with such variable composition.
Cone-in-cone structures are identifiable by their distinctive conical appearance. They are composed of concentric cones nested inside each other. The actual composition of the cones is variable and dependent on the environment in which they were formed, with the majority of the cone-in-cone structures being composed of calcite with thin layers of clay between cones. There are also, more rarely, structures composed of siderite, gypsum, pyrite. There are also some instances of cone-in-cone occurring within coals. Often the cone-in-cone will be found as features of calcite layers within a shale., and rarely within a dedolomite (calcitized dolomite)
Winners: Kelda 3 points
Name that volcano riddle.
I am the largest of the group of 3 –
I am the legendary 1 of 3 –
I am closely associated with an ancient 3 –
I am the sacred ritual source of 3.
The answer to Suzies riddle was Olympus Mons.
The highest volcano and mountain in the entire solar system. I am not an expert on Martian volcanoes but have the privilege to present them to visitors with a special program called Uniview in my museum rather often. So i am not so very happy about this riddle, though i am really graetful Suzie is supplying me with riddles and helps keeping the blog alive in times when there is not much up for us vocanoholics. And the rest of the gang enjoyed the riddle and learned many new things hunting for the correct answer. The reason why i am not happy about this answer is, because Olympus Mons is not the largest of the 3 but lies close to the 3 volcanoes which are almost the same size called Tharsis Montes.
So here is what i (think) i know about Olympus Mons.
It is almost 26 km high and i heard it reaches this spectacular hight because Mars does not have plate tectonics and so the volcano stayed above that hotspot for a long time and did not move away as it would have if it would lie on earth. Nasa announced not so long ago that the last eruption might be only a few million years in the past.
But this is just my layman knowledge and might be wrong.
Here is an excerpt on Mars written by Alan and you can also find it at https://volcanocafe.wordpress.com/2012/01/23/we-are-not-alone-out-there/
Unlike the almost totally volcano covered surface of Venus, Mars has volcanism concentrated in 4 provinces together with extensive volcanic plains. One of the greatest shield volcanoes so far located in the Solar System, Olympus Mons, with a basal diameter around 600km (Iceland has a width – from Snaefellsness to Egilsstaðir – of around 500km) with a height of some 25000m is located in the Tharsis Province. The vast size has been attributed to the presence of a very long-lived mantle hotspot and a lack of plate tectonics, the latter as having prevented Hawaii reaching similar proportions. The periphery of Mons Olympus is a cliff-like edge some 8km in height the origin of this feature as yet unknown. High resolution images show fresh surfaces to flows, as recent as 20 million years has beed suggested.
Olympus Mons off to the apparent north-west of 3 volcanoes – Arsia Mons, Pavonia Mons and (top) Ascraeus Mons. The green coloured area to the ‘north and west’ of Olympus Mons is a vast lava field from this feature.
Alba Mons, also on Tharsis – the very large red region at the top of the diagram above, is perhaps less obvious than Olympus Mons, having a very shallow slope around 0.5 degree and 7km high, but the volcanism covers a much greater area, with flow fields of highly fluid lava extending up to 1300km from the eruptive centres. The age of this structure has been suggested at c3.2×10^9 years.
Images for some Martian structures can be seen here:
Map of Mars: http://www.joelertola.com/grfx/mars/mars_lg.jpg
I collected some quotes by GeoLurking which might be interesting for you. We were wondering at that time if Olympus Mons was visible with the naked eye :
0.4 minarc x 60 = 24 arc-seconds.
In the travels of Earth and Mars about their respective orbits, at the closest, they get to about 0.37 AU, or 55,917,844 kilometers. Max distance is 2.68 AU, or about 400,256,033 km.
At minimum Earth-Mars range, the crater on Olympus Mons is about 0.30 arc-seconds across for the long axis, 0.23 arc-seconds for the short axis.
At minimum Earth-Mars range, the Tharsis mountains are about 5.7 arc-seconds long, and the entire edifice of Olympus Mons is 2.02 arc-seconds, cliff face to cliff face.
At minimum Earth-Mars range, something on the surface would have to extend for 6506 kilometers in order to achieve 24 arc-seconds of angular separation from one end to the other, to be discernible with the perfect.. un-aided eye.
The 451 km diameter Huygens crater is within 571 km of dead center alignment with the Olympus Mons antipode. (the crater rim is within 314 km) and it is 915 km from the centerline for the antipodes for the Tharsis mountains… on the opposite direction.
Given the number of smaller and later impacts that cover it’s ejecta field… it’s has to be pretty old.
Based on crater accumulation rates… the estimated age of Olympus Mons is somewhere between 0.1 and 1.1 billion years, with a best estimate of 0.4 billion.
Syrtis Major Planitia 2.6 to 3.8 billion, best estimated 3.5 billion.
(Note: Billion -> 1 x 10^9)
Nearby… are dikes. Hellas Planitia is a probable flood basalt feature… whether the dikes are related to either one is up for debate. They don’t seem to be aligned with Huygens crater, merely running past it.
Huygens-Hellas giant dike system
I gave the answer though it was ment as a joke when i said it 1 minute before KarenZ. I have not yet decided if i want to have this point or give it to KarenZ.
I also do not know if Suzie wants to hand out more points for some others because for example Ursula found a lot out about the ritual mentioned in the riddle.